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H. MAXIM. PROCESS OF MANUFACTURING GARBONS- No. 247,083.- Patnted Sept. 13;18.8 1.

- Lamps, of which the following is a specifica- [UNITED Y ninAM .i nxrn, or BROOKLYN, AssIcN'on are-Tire mm) sir EIJECTRIO'LIGHTINQ-QQMPANY,'QFNEW,YORK,

PRocEsjLofF:MANUFACTURING Camus. "i

I SPECIFICATION forming part of Letters Patent No. 247,083, dated September 13, 1881. A pplicalionifiled April 6, 1881. (No model.)

To all whom it may concern:

Be it known that I, HIRAM S. MAXIM, of the city of Brooklyn, county of Kings, and State of New York, have invented certain new and usefnl Improvements in the Process of Manufacturing Carbon Loops for Incandescent Electric tion.

My invention relates more particularly to the production of the carbon loops designed for use with incandescent lamps, or those that give light by the incandescence of a strip of carbon included in an electric circuit and inclosed in a glass globe. The invention may, however, be applied tothe manufacture of carbons for such other kinds of lamp as may require carbons of very small diameter bent 0" cut into circular or similar form; and it consists in first cutting out a straight blank, which is subsequently carbonized and then bent into the form of a loop or horseshoe,in which form it is permanentl y set by electrically heating the same, as will more fully appear hereinafter. v

Hitherto in theman ufacture of the loops and other carbon conductors of a similar character it has been usual to cut the blanks in the first instance from some fibrous material, giving to them the shape in which they are to be ultimately used. In lieu of this they were also formed by bending a straight blank to the desired shape and carbonizing it while so bent, it being found that by so doing the strips re-v tained their arch shape. Both of these processes involve the employment of special appliances in the carbonization or baking, which add greatly to the expense of the completed v carbons. It is also difficult to obtain by either method strips in which the resistance is dis tributed equally throughout the whole carbon.

To overcome many of the previously-encountered ditficulties in the preparation of a large number of perfcctcarbons, I proceed as follows: I first cut out from suitable fibrous materials a number of straight blanks of small diameter at the central portion and gradually widened toward the ends, and these I carbonize, preferably by the process described in my Patent of 5 July 20, 1880, No. 230,309. On being taken" from the muflle, the strips are bent over in the form of an arch or loop, and their ends being i secured in temporary holders or clamps, they 3 are placed in a closed vessel containing a carbonaceous gas-such as a volatilized hydrocarbon or cyanogen gas-and raised to a high heat by an electric current, or in other wellknown ways. bon is deposited on the strips until they are brought to the required resistance, and on bein g removed they-will retain the form to which they have been. bent.

The accompanying drawings illustrate (leviccs for carrying out the final steps in my process.

Figure 1 represents the blank before carbonization. Fig. II is the same after being baked or carbonized. Fig. Ill represents the apparatus employed in building up the carbons and setting themin shape.

C is a glassreceiver connected with an exhaust-pump. by means of a tube. 1.

G is a small chamber containing gasoline or other volatile h ydrocarbomcommunicatin g with theinterior of U by means of thetube H,

providedwith two cocks, E F, placed a short distance apart.

B B are clamping-jaws t'orretaining the ends of a carbon strip, A, and form the terminals of an electric circuit, in which is included a resistance, R, and switch S.

The operation is as follows: The carbons, in any suitable number, are secured to clamps B 13, under the receiver 0, and the air withdrawn. By closing first the cock E and opening F the part of tube H bet-ween the two is filled with hydrocarbon vapor. This is allowed-to enter the receiver 0, when the current is directed by switch S through the carbons. The latter are allowed to build up for a sufficient length of time, and are then removed and secured in the usual manner in the lamps. A conductor is thus produced that is remarkably free from flaws, is very resilient, and capable of withstanding a very high degree of incandescencc.

By this means a carbon may be formed which has no disposition to alter the shape to which hires,

,PAT ENTL QaOrFIcn. 1

By the action of the heat carit is set, which may be that of an arch, loop,

- ring, or even spiral.

Having thus described my invention, what 1 claim as new, and desire to secure by Letters Patent, is

1. The process of manufacturing carbon conductors for electric lamps, which consists in cutting the-blanks from fibrous material, carn'iosphere of carbonaceous gas or vapor, sub- 10 (ionizing-file same, bending the carbonized stantially asset forth. strips into the desired shape, and then eleotri- In testimony whereof I have hereto set my can beating them for giving them a, permahand. this 4th day of April, 1881.

5 nent set, as described.

2.. Themethod herein described of fixing a carbon strip in any form to which it may have been bent, by subjecting the same while bent to the action of an electric current in an at- HIRAM S. MAXIM. Witnesses:

HENRY HINE, UHAs. G. PAGE. 

